Harmy said:
And I pretty much had all that figured out, I just need to know really, if (and how) I can get lossless HD audio from the PC that way.

Yes, as long as you have PC Video Card -> HDMI -> AVR, you can directly bitstream the lossless audio through the HDMI. This can be enabled pretty easily in MPC-HC (in Options, go to Interal Filters, click Audio Decoders and under Bitstreaming check all the boxes for the audio types that you want to bitstream). As long as you have an AVR that can decode Dolby TrueHD and DTS-HD MA, this will do exactly what you want.